The present invention relates to an infeed system of a rotary press in which a paper web of a web roll supported by a web roll supporting means of a rotary press is supplied for a succeeding process such as a printing process in a printing section by means of infeed roll by which a paper web traveling amount can be controlled.
In a case where a plurality of paper webs printed by a rotary press are gathered or collated by a collator, it is required for the paper webs to have the same top and bottom dimensions with each other. Particularly, for a business-form rotary press carrying out printings on paper webs which are required to be gathered or collated by the collator after printings, it is very important for the paper webs to have constant top and bottom dimensions with each other even if materials, basis weights thickness or the like of paper webs to be collated are different from each other.
However, as is known, where the paper webs are fed by an infeed system of the rotary press, the traveling amounts thereof differ from each other in accordance with the materials, basis weights thickness or the like of the paper webs. Accordingly, in a case where such various different kinds of paper webs are printed, the traveling amounts differ from each other even if the paper webs are printed under the same printing conditions, hence providing inconvenience at the time when paper webs are gathered or collated.
In order to eliminate such defects, a first prior art providing a solution is disclosed for example, in Japanese Patent Publication No. HEI 4-51456. This prior art discloses a structure, as shown in FIG. 2, comprising a plate cylinder 1, a blanket (rubber) cylinder 2, an impression cylinder 3, and a differential speed change gear 5 disposed in a power transmission means for the blanket cylinder 2 and the impression cylinder 3 which put a paper web between them, carry out printing on the paper web and make the same travel. The differential speed changer 5 comprises a Harmonic Drive (Trade Name) a speed of which is adjustable by an adjustment motor 4. In this structure, the plate cylinder 1, the blanket cylinder 2 and the impression cylinder 3 are coupled in series to each other and rotated at the same rotation number in directions reverse to each other.
According to this first prior art, the rotating speed of the impression cylinder 3 is adjusted by the differential speed change gear 5 with respect to the rotating speed of the blanket cylinder 2 thereby to change the traveling amount of the paper web. That is, in a case of thick paper web, the rotating speed of the impression cylinder 3 is decreased, and on the other hand, in a case of thin paper web, the impression cylinder 3 is adjusted reversely. In this manner, the traveling amount of the paper web can be changed.
A second prior art also provides a solution, in which the rotating speed of the infeed roll is adjusted in accordance with the change of the tensions in consideration that tensions of paper webs passing between rolls are changed in accordance with the change of the paper web thickness.
FIG. 3 is a schematic view showing the structure of the above second prior art. With reference to FIG. 3, a paper web 7 fed from a web roll 7a is fed in the paper web traveling direction and wound up in substantially S-shape around two infeed rolls 8a and 8b, which are rotated in directions reverse to each other at the same rotating speed, and the paper web 7 is then supplied on a side of the printing unit 9, i.e. downstream side, in the paper web traveling direction.
The infeed rolls 8a, 8b and the printing unit 9 are driven by a drive line 10 from a press machine side through gear boxes 11a and 11a, respectively. In the gear box 11a driving the infeed rolls 8a and 8b, there is housed the differential speed change gear 5 having the speed ratio (gear ratio) which is adjustable by the adjusting motor 4 as like as in the first prior art mentioned above. Further, first and second tension detectors 12a and 12b for detecting the tension of the paper web 7 are arranged on both the upstream side and downstream side of the infeed rolls 8a and 8b, respectively.
In FIG. 3, reference numeral 13 denotes a controller for generating a speed change signal to the motor 4. The controller 13 carries out a comparison operation of a detection value T1 fed back from the second tension detector 12b disposed downstream side of the infeed rolls 8a and 8b with a set value T2 preset by a setting device 14, and the controller 13 then generates a signal, to the motor 4, for adjusting the differential speed change gear 5 so as to rotate the infeed rolls 8a and 8b at the rotating speed at which the compared value becomes zero. Accordingly, the infeed rolls 8a and 8b are controlled so that the tension T1 of the paper web 7 detected by the second tension detector 12b always becomes equal to the set value T2 set by the setting device 14 thereby to keep constant the traveling amount of the paper web 7. Further, reference numeral 15 denotes a brake means operating in response to the detection value detected by the first tension detector 12a. 
Further, it is to be noted that the term xe2x80x9ctraveling amountxe2x80x9d used herein means a traveling distance (length) per unit rotation number of a prime mover (motor) of the rotary press, a traveling distance (length) per one rotation of the infeed roll or a traveling distance (length) per unit time.
In the first prior art mentioned above, when paper webs having different thicknesses are fed by the blanket cylinder 2 and the impression cylinder 3 as the infeed rolls with the tension applied to the paper web in the paper web traveling line and being maintained constant, the traveling amount of the paper webs differ in accordance with the thicknesses of the paper webs. Because of this reason, in the prior art, in order to make constant the traveling amounts of a plurality of paper webs having different thicknesses, it is necessary to obtain an aimed (target) traveling amount of the paper web by experimentally calculating a preset value to be inputted into the adjusting motor 4 for determining the speed ratio (gear ratio) of the differential speed change gear 5 with respect to each of the paper webs, measuring an absolute value of the paper web traveling amount by means of scale and so forth, in an operation stop condition of the printer,and then amending or correcting a feed amount by the infeed roll. Accordingly, it is very difficult to make travel the plurality of paper webs having different thicknesses at the same traveling amount. Furthermore, because the wind-up diameter of the web roll is changed as the paper web is fed, it is sometimes necessary to check the traveling amount at an intermediate time of the feeding as well as the feed-start time according to the condition of the web. In such case, some problems were caused on the printing process.
On the other hand, in the second prior art mentioned above, the detection value T1 and the set value T2 are compared by the controller 13, and the signal for operating the adjustment motor 4 to adjust the motor rotating speed so as to make zero the compared value is generated to the motor 4. According to this operation, the tension of the paper webs having different thicknesses at the traveling time can be made constant and the traveling speed of the paper webs can be hence maintained constant.
However, the detection value T1 inputted into the controller 13 is a value of the tension, which is a predetermined tension applied to the paper web 7, and therefore, this value T1 is the value detected at time when the paper web is elastically and plastically deformed by the tension. Accordingly, even if the detection value T1 is the same with respect to the different paper webs, the actual traveling amounts of the paper webs having different thicknesses and different elastic deformations due to the thickness difference, become different from each other. Thus, the correction or amendment of this matter is very troublesome to be handled.
In an actual operation, in order to obtain a precise traveling amount of the paper web, it is necessary to actually measure the absolute value of the paper web traveling amount by means of a scale or the like after once stopping the feeding of the paper web and then to correct and preset the set value T2 of the tension in conformity with the measurement result of the absolute value of the traveling amount. These workings are made in accordance with the experience of the workers, requiring the skill and, hence, being troublesome and inconvenient. That is, in such a prior art, it is difficult to carry out the presetting of the fundamental traveling amount.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide an infeed system of a rotary press capable of accurately measuring an absolute value of traveling amount of a paper web regardless of material, basis weight (thickness) or the like of the paper web, always maintaining the traveling amount thereof to an aimed (target) traveling amount and making constant the traveling amount of the paper web in conformity with gathering or collating operation of a collator.
This and other objects of the present invention can be achieved by providing, in one aspect, an infeed system of a rotary press in which a traveling amount of a paper web is controlled by infeed rolls which feed the paper web to a subsequent process, said system comprising:
traveling amount measuring means disposed on a traveling line of the paper web fed by the infeed rolls for measuring the traveling amount of the paper web in a tension free state that is created between the infeed rolls by rotating the infeed rolls in a same direction and at a same speed, and for generating a signal representing the measured traveling amount; and
traveling amount controlling means for controlling the traveling amount of the paper web fed by the infeed rolls in response to the signal generated by the traveling amount measuring means.
In a more concrete aspect, there is provided an infeed system of a rotary press for controlling a traveling amount of a paper web fed from a web roll, comprising:
at least first and second infeed rolls disposed on a downstream side of the web roll for feeding the paper web in a traveling direction in a tension free state that is created between the first and second infeed rolls by rotating the infeed rolls in a same direction and at a same speed;
infeed roll driving means for driving the first and second infeed rolls, said infeed roll driving means including infeed roll rotation speed adjusting means for adjusting the rotation speed of said infeed rolls, respectively;
traveling amount detection means for detecting the traveling amount of the paper web and for generating a signal representing the detected traveling amount;
rotation speed detection means for detecting the rotation speed of the infeed rolls and for generating a signal representing the detected rotation speed; and
control means operatively connected to said infeed roll driving means for controlling the traveling amount of the paper web in accordance with the signals generated by the traveling amount detection means and the rotation speed detection means.
In a more specific embodiment, the infeed system further comprises a third infeed roll disposed on a downstream side of the second infeed roll to be rotatable in a direction reverse to that of the second infeed roll.
According to the infeed system of the rotary press of the present invention mentioned above, the amount of traveling the paper web from the web (roll) to the subsequent stage or process such as printing process is measured under the no-tension (tension free) state on the paper web traveling line by the traveling amount detector, and accordingly, the traveling amount measured under this state can be measured as an absolute value with no relation to the material of the paper web and the basis weight thickness thereof. The thus measured value is compared with the target traveling amount thereby to control the traveling amount of the paper web of the infeed rolls by the control means.
The traveling amount of the paper web by means of infeed rolls can be mechanically controlled in accordance with the traveling amount of the paper web under the tension free state, and accordingly, in a case where paper webs different in their materials, basis weights or thicknesses and the like are fed, the traveling amount of the paper webs can be always maintained substantially to the target traveling amount and the collation by the collator can be made properly constant.
Furthermore, it is not necessary to carry out the measurement or correction of the traveling amount by stopping the operation of a machine at every time when a different paper web is used, thus eliminating loss of working time, being convenient and advantageous.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.